Respiratory System Parasites

There are many parasites that can cause diseases of feline respiratory system. Most of them are caused by roundworms, flatworms, mites protozoansand . These parasites occur in the the lungs, nares, nose or throat of cats and can cause life-threatening diseases in animals and humans.

Eucoleus boehmi (nasal capillarid) is a roundworm that occurs both in dogs and cats. Cats can be infected through accidental ingestion of earthworms. Infected cat may forcefully tap its nose against the ground, trying to expel the nasal discharge from its nose.

Cuterebra is a large larva that is often found in the skin of dogs and cats. Cats are infected through contact with rodents, mainly in the spring time, and young kittens may be infected by the larva carried on the fur of their mother. Infected animals may have persistent sneezing or nasal discharge, swelling over the nose, labored breathing with a bloody nasal discharge, and mouth and throat swelling.

Toxoplasma gondii is a microscopic internal parasite that causes toxoplasmosis which reveals itself most commonly as respiratory disease. Pneumonic toxoplasmosis often develops in cats that have other current infections such as Feline Immunodeficiency Virus (FIV). The disease causes other complication and is usually fatal. Cats with pneumonic toxoplasmosis usually have labored breathing, fever, lethargy, abdominal tenderness, and loss of appetite. Cats may not show any signs of the infection, but occasionally they may develop a systemic disease that affects multiple organs.

Paragonimus kellicotti is a flatworm that occurs in the lungs of cats and dogs. The main natural hosts of the adult parasites are badger, mink, otter and weasel which get infected through ingestion of snails. Dogs and cats commonly become infected by eating fresh-water crabs, crayfish and rodents. Kittens may be infected by their mother. Dogs and cats will begin to shed eggs 5 to 7 weeks after infection. Signs are usually mild and may include occasional coughing. In case of severe infection, the animal can have labored breathing, a sudden attack of coughing and accumulation of air and gas in the lung cavities from migrating worms. Occasionally, sudden death may occur from the breaking of the membrane that envelops the lung (pleura).

Capillaria aerophila, a trichuroid parasitic nematode affecting the respiratory systems of cats and dogs. The adult lungworms live embedded in the epithelia of the bronchioles, bronchi, and trachea of the definitive host. After mating, the females lay eggs that are coughed, swallowed, and released via feces into the environment, where they undergo further development through the infectious stage. Animals become infected by ingesting environmental embryonated eggs or earthworms, which are considered an intermediate host. Pulmonary capillariosis is considered may not result in serious disease, although the parasite may cause a chronic bronchitis with sneezing, wheezing, and chronic dry cough. When bacterial complications occur, the cough may become moist and productive, leading to bronchopneumonia and respiratory failure.2

Preventing Internal Parasite Infection

Have your pet tested for parasites on an annual basis. Never feed your pet on the ground. Use clean dishes for your pet's food and water. Always clean up your cat's stools to reduce soil contamination. Wash your hands after working in dirt that might be soiled by cats.


  1. Updates on feline aelurostrongylosis and research priorities for the next decade. Hany M. Elsheikha,corresponding author Manuela Schnyder, Donato Traversa, Angela Di Cesare, Ian Wright, and David W. Lacher
  2. Molecular Detection of Capillaria aerophila, an Agent of Canine and Feline Pulmonary Capillariosis Angela Di Cesare,a Giuseppe Castagna,a Domenico Otranto,b Silvana Meloni,a Piermarino Milillo,a Maria Stefania Latrofa,b Barbara Paoletti,a Roberto Bartolini,a and Donato Traversacorresponding authora. J Clin Microbiol. 2012 Jun; 50(6): 1958–1963.


  1. Canine and feline cardiopulmonary parasitic nematodes in Europe: emerging and underestimated Donato Traversa,corresponding author1 Angela Di Cesare,1 and Gary Conboy2 Parasit Vectors. 2010; 3: 62.

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